net/netdev: Change SIOCSCANBITRATE to require interface down.

Previously, SIOCSCANBITRATE brought the iterface up to ensure changes
where immediately applied. This was confusing, see
https://lists.apache.org/thread/g8d0m6yp7noywhroby5br4hxt3r4og2c
Now SIOCSCANBITRATE fails is interface is up.
All existing SocketCAN drivers updated.

Signed-off-by: Carlos Sanchez <carlossanchez@geotab.com>

net/netdev/netdev_ioctl.c

@@ -1176,8 +1176,18 @@ static int netdev_ifr_ioctl(FAR struct socket *psock, int cmd,
 #endif
 
 #if defined(CONFIG_NETDEV_IOCTL) && defined(CONFIG_NETDEV_CAN_BITRATE_IOCTL)
-      case SIOCGCANBITRATE:  /* Get bitrate from a CAN controller */
       case SIOCSCANBITRATE:  /* Set bitrate of a CAN controller */
+        if (dev->d_flags & IFF_UP)
+          {
+            /* Cannot set bitrate if the interface is up. */
+
+            ret = -EBUSY;
+            break;
+          }
+
+        /* If down, fall-through to common code in SIOCGCANBITRATE. */
+
+      case SIOCGCANBITRATE:  /* Get bitrate from a CAN controller */
         if (dev->d_ioctl)
           {
             FAR struct can_ioctl_data_s *can_bitrate_data =